You are being interviewed to give them the best part of £10k and that doesn't guarantee you a job.
So the interview process is pretty easy really... it's nearly all competency-based... "when have you shown leadership/adaptability/resilience" etc.
Once you pass, pay your £10k, and do the MCC... THEN if your training report is good enough (i.e. average or better) they will stick you into the hold pool behind all their modular and integrated pilots. So you're in the 3rd priority group behind all those. And they've got around 200 integrated people a year going through.